Metamaterial also known as artificial electromagnetic material is a new academic vocabulary in the field of physics in the 21st century and is usually issued on different kinds of scientific literatures. The metamaterial includes three important characteristics: (1) the metamaterial is a composite material usually with novel artificial structure; (2) the metamaterial usually has extraordinary physical characteristic, which does not exist in the nature materials; (3) the characteristics of the metamaterial are not determiend by the inherent characteristic of the constituent materials, but mainly dependent on the artificial structures.
That is to say, the metamaterial is a material that is composed of a plurality of artificial microstructures which are used as basic units and are placed in a specific spatial arrangement. Moreover, the metamaterial is a new material with specific electromagnetic response, and the characteristics of the electromagnetic response are dependent on the characteristics of the artificial microstructures. By orderly designing of the structure on crucial physical size of the material, some limitations of the nature law can be overcome, therefore obtaining the metamaterial characteristic that is beyond the inherent ordinary characteristic in the nature.
The metamaterial includes a plurality of artificial microstructures, and the electromagnetic responses of the artificial microstructures mainly depend on the topological characteristics and the size of the structural units of the artificial microstructures.
The metamaterial further includes a substrate attached by the artificial microstructures. The substrate is a structure that serves to support the arranged artificial microstructures, and can be made of any nonmetal material different from that of the artificial microstructures.
The artificial microstructures and the substrate are superimposed together to generate an equivalent dielectric constant ξ and an equivalent permeability μ in the space, both of which respectively correspond to the electric field response and the magnetic field response of the material. Thus, the design of the artificial microstructures of the metamaterial is most crucial part in the field of metamaterials. Therefore, it is becoming a major problem in the development of modem technology that how to obtain a metamaterial, and further improve the electromagnetic characteristic of the existing electromagnetic materials, and replace the existing electromagnetic materials to achieve in practice.